HIGH-SPEED DETECTION METHOD OF METALLIC ELEMENTS OF DENTAL RESTORATION FROM ALLERGY SUSPECTED PATIENTS BY X-RAY FLUORESCENCE ANALYSIS

对于金属过敏的诊断和治疗，了解疑似患者修复体的金属元素是必不可少的。这项研究旨在证实这样一种假设，即尽管从患者的口腔中采集了非常少量的样本，但显微X射线荧光分析可以快速提供有关金属元素的有效信息。样本是通过用折叠的研磨膜的锐角摩擦修复体来收集的。用XGT-2700型微型X射线荧光仪(日本Horiba的XGT-2700型)分析样品，该仪器产生直径为0.1 mm的X射线束。常规分析最多需要8分钟，包括从患者口腔中采集样本，对样本进行充电，检测特征X射线，最后显示结果。根据通过测量标准金膜的X射线强度得到的校准线，估算出金膜上的金样的量为几十纳米克。在这种微弱样品的情况下，由于缺乏足够的信息深度，每个元素的灵敏度随着其特征X射线能量的增加而降低。为了纠正这种强度异常，测量前在研磨膜上覆盖一层塑料薄膜。对于典型的牙科合金，主要成分的评估与制造表明的值有几个百分点的偏差。此外，可以高可靠性地检测到0.5%或更多的添加元素，如锌。这些结果表明，口腔修复体金属元素的快速检测方法对金属过敏的诊断是非常有用的。

For diagnosis and treatment of metal allergy, it is essential to know the metallic elements composing the restorations in a suspected patient. This research aimed to confirm the hypothesis that microscopic X-ray fluorescence analysis can quickly provide effective information on the metallic elements, in spite of a very small amount of sample collected from the patient's mouth. The sample was collected by rubbing the restorations with the sharp corner of a folded lapping film. The sample like a spot at the corner was analyzed by a microscopic X-ray fluorescence equipment (XGT-2700, Horiba, Japan), which generates X-ray beam of 0.1 mm in diameter. Routine analysis took 8 minutes at most, including collection of the sample from the patient's mouth, charge of the sample, detection of the characteristic X-rays, and final display of the result. Based on the calibration line that was obtained by measuring X-ray intensity from standard gold films, the amount of gold sample on the film was estimated to be several tens nanogram. In the case of such a faint sample, the sensitivity for each element decreases with the increase of its characteristic X-ray energy because of the lack of sufficient information depth. To correct this intensity abnormality, the lapping film was covered with a plastic film before measurement. For typical dental alloys, main components were evaluated within a few percents deviation from the values indicated by manufacture. Furthermore, additive elements of 0.5 % or more, such as zinc, could be detected in high reliability. From these results, it is concluded that the high-speed detection method of metallic elements of dental restoration is very useful for diagnosis metal allergy.